'\" et
.TH SCHED_SETPARAM "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
sched_setparam
\(em set scheduling parameters
(\fBREALTIME\fP)
.SH SYNOPSIS
.LP
.nf
#include <sched.h>
.P
int sched_setparam(pid_t \fIpid\fP, const struct sched_param *\fIparam\fP);
.fi
.SH DESCRIPTION
The
\fIsched_setparam\fR()
function shall set the scheduling parameters of the process specified by
.IR pid
to the values specified by the
.BR sched_param
structure pointed to by
.IR param .
The value of the
.IR sched_priority
member in the
.BR sched_param
structure shall be any integer within the inclusive priority range for
the current scheduling policy of the process specified by
.IR pid .
Higher numerical values for the priority represent higher priorities.
If the value of
.IR pid
is negative, the behavior of the
\fIsched_setparam\fR()
function is unspecified.
.P
If a process specified by
.IR pid
exists, and if the calling process has permission, the scheduling
parameters shall be set for the process whose process ID is equal to
.IR pid .
.P
If
.IR pid
is zero, the scheduling parameters shall be set for the calling process.
.P
The conditions under which one process has permission to change the
scheduling parameters of another process are implementation-defined.
.P
Implementations may require the requesting process to have appropriate
privileges to set its own scheduling parameters or those of another
process.
.P
See
.IR "Scheduling Policies"
for a description on how this function affects the scheduling of
the threads within the target process.
.P
If the current scheduling policy for the target process is not
SCHED_FIFO, SCHED_RR,
or SCHED_SPORADIC,
the result is implementation-defined; this case includes the
SCHED_OTHER policy.
.P
The specified
.IR sched_ss_repl_period
shall be greater than or equal to the specified
.IR sched_ss_init_budget
for the function to succeed; if it is not, then the function shall
fail.
.P
The value of
.IR sched_ss_max_repl
shall be within the inclusive range [1,{SS_REPL_MAX}] for the function
to succeed; if not, the function shall fail. It is unspecified whether the
.IR sched_ss_repl_period
and
.IR sched_ss_init_budget
values are stored as provided by this function or are rounded to
align with the resolution of the clock being used.
.P
This function is not atomic with respect to other threads in the
process. Threads may continue to execute while this function call is in
the process of changing the scheduling policy for the underlying
kernel-scheduled entities used by the process contention scope
threads.
.SH "RETURN VALUE"
If successful, the
\fIsched_setparam\fR()
function shall return zero.
.P
If the call to
\fIsched_setparam\fR()
is unsuccessful, the priority shall remain unchanged, and the function
shall return a value of \-1 and set
.IR errno
to indicate the error.
.SH ERRORS
The
\fIsched_setparam\fR()
function shall fail if:
.TP
.BR EINVAL
One or more of the requested scheduling parameters is outside the range
defined for the scheduling policy of the specified
.IR pid .
.TP
.BR EPERM
The requesting process does not have permission to set the scheduling
parameters for the specified process, or does not have appropriate
privileges to invoke
\fIsched_setparam\fR().
.TP
.BR ESRCH
No process can be found corresponding to that specified by
.IR pid .
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "Scheduling Policies",
.IR "\fIsched_getparam\fR\^(\|)",
.IR "\fIsched_getscheduler\fR\^(\|)",
.IR "\fIsched_setscheduler\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<sched.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
